Improve Lab Accuracy for Better Water Analysis

Transcription

1 Improve Lab Accuracy for Better Water Analysis December 14, 2017 Webinar Moderator Nathan Edman Standard Methods Manager American Water Works Association Nathan oversees and manages the electronic and print production of Standard Methods for the Examination of Water and Wastewater and is in charge of a majority of the AWWA chemical standards committees. Nathan received his Bachelor of Science Degree in Chemistry from the University of Arizona. 2 Please consider the environment before printing. 1

2 Enhance Your Webinar Experience Close Programs Instant messengers Other programs not in use GoToWebinar Support 3 Webinar Survey Immediately upon closing the webinar Survey window opens Thank you! 4 Please consider the environment before printing. 2

3 Products or Services Disclaimer The mention of specific products or services in this webinar does not represent AWWA endorsement, nor do the opinions expressed in it necessarily reflect the views of AWWA AWWA does not endorse or approve products or services 5 Panel of Experts Jessica McVay Technical Support Specialist Metrohm USA Lori Spafford Titration Product Manager Metrohm USA 6 Please consider the environment before printing. 3

4 Agenda I. What is Titration? Jessica McVay II. III. More on Endpoint Detection What s the Big Difference? Buret Titration vs. Autotitration Jessica McVay Lori Spafford IV. Application Tips & Tricks V. So Many Samples, So Little Time Lori Spafford Lori Spafford 7 Ask the Experts Jessica McVay Metrohm USA Lori Spafford Metrohm USA Enter your question into the question pane at the lower right hand side of the screen. Please include your name and specify to whom you are addressing the question. 8 Please consider the environment before printing. 4

5 Rationale & Objectives Firm up titration and electrode fundamentals Understand how autotitration can improve accuracy Overview of common water analysis tips and tricks Hear about technology improvements for colorimetric titration and high-throughput laboratory needs Identify potential areas of improvement in your lab operations 9 Today s Topics Review fundamentals of titration Understand how electrodes work Getting better results from colorimetric titrations Common water analysis tips & tricks Improving throughput with a new concept in automation Live question and answer 10 Please consider the environment before printing. 5

6 What is Titration? Fundamental review 11 What is titration? Start T T T Endpoint T T T Finish T T T T Titrant reagent with known concentration A Analyte unknown in sample T T T A A A T A T A T A T A T A T A A A A T A T A T A T A T A T A 12 Please consider the environment before printing. 6

7 What was titration? Manual additions made by glass buret Manual control controlled by analyst Optical detection for visual confirmation the endpoint has been reached Challenges of Manual Titration Need a neutral background Visibility of indicator in colored samples Consistent decision making between analysts Careful data recording and calculation Even an experienced bench chemist can require 5 minutes per titration Please consider the environment before printing. 7

8 What is titration now? Advanced dosing, titrating, and liquid handling Sophisticated measuring sensors What is titration now? Thorough data evaluations and management Secured user administration Please consider the environment before printing. 8

9 Endpoint Detection Different ways to detect Color change mv change Temperature change Some of the challenges Color change is subjective between analysts Hanging burets are difficult to read Manual calculations subject to human error 17 More on Endpoint Detection How do electrodes work? 18 Please consider the environment before printing. 9

10 Measurements with Electrodes Definition An electrode which produces a voltage dependent (logarithmically) on the concentration of a selected substance. ISE e.g. H (ph electrodes) ISE e.g. F, Cl, Cu, Pb, Surfactant Redox Electrodes Metal Electrodes e.g. Ag, Pt 19 Potentiometric Measurement What is needed? 1. Measuring electrode 2. Reference electrode 3. ph/voltmeter meter 4. Sample Ref. U, mv Meas. Measuring principle: Measurement of potential differences 20 Please consider the environment before printing. 10

11 Combined Electrode Systems Ref. Meas. Combined How can I tell what type of electrode system I have? Fill port & glass bulb 21 Closer Look at Combined Electrodes electrode head Ag/AgCl cartridge refilling opening glass shaft diaphragm electrode tip glass membrane Please consider the environment before printing. 11

12 Membrane Layers ph glass electrode responds to H + ions in solution hydrated layer (~0.1 mm) alkaline 23 Same Function, Different Shapes Ball (12 mm) Titration Needle (4 mm) Measurement Half ball (12 mm) Titration Micro cylinder (3 mm) Measurement Cylinder Measurement/ Titration Flat membrane Measurement /Titration 24 Please consider the environment before printing. 12

13 Reference Diaphragm Electrolyte solution must be in contact with sample solution Outflow of electrolyte due to simple hydrostatic pressure Fill port must be open for this to occur A B Outflow too low (A) Contaminate reference Optimal outflow (B) Must refill electrode regularly 25 Why is calibration needed? Electrode response is a mv signal The mv needs to be correlated to a ph value The factors that influence this relationship are slope and zero point (intercept) 26 Please consider the environment before printing. 13

14 Why is calibration needed? Aging of the glass membrane of the sensor or blockage of the diaphragm Change of electrode zero point and slope Meter is adapted by calibration to the actual characteristics Calibration should be done frequently 27 Color Changing Titrations Need an Optical Sensor Think hardness titrations Optrode sensor detects color-changing endpoints Wavelength, nm For Color Change To Useable Range 470 Yellow Orange/Red Red Violet/Purple Blue Blue/Green Green Black/Turbid Please consider the environment before printing. 14

15 How the Optrode Works Choose correct wavelengths Connect directly to titrator Sample solution passes through optical window Signal converted to mv reading and is graphed like traditional potentiometric titration 29 What s the big difference? Manual buret titration vs. autotitration technology 30 Please consider the environment before printing. 15

16 What Matters the Most Achieve accurate results Perform repeatable analysis Reduce or remove human error Achieving Accurate Results Manual Titrations Buret increment limitations Autotitrator Precise buret increments Please consider the environment before printing. 16

17 Achieving Accurate Results Manual Titrations Manual control of titration speeds Autotitrator Controlled, dynamic titration speeds Performing Repeatable Analysis Manual Titrations Visual decision making Autotitrator Absolute potential measurements Please consider the environment before printing. 17

18 Performing Repeatable Analysis Manual Titrations Endpoint volumes read by analyst Autotitrator Precise endpoint volumes reported by instrument Performing Repeatable Analysis Example Scenario: Data trending between shift operators Please consider the environment before printing. 18

19 Reducing Human Error Over titration Manual Titrations Autotitrator Endpoint is never missed Reducing human error Manual Titrations Manual data recording, Manual data recording, calculations, data entry calculations, & data entry Autotitrator Digital data collection, automatic automatic calculations calculations & LIMS upload & LIMS upload Please consider the environment before printing. 19

20 Application Tips & Tricks Make Lab Analysis Easier! 39 Common Titration & Ion Analysis ph Measurement Conductivity Alkalinity Chlorine Total Hardness Calcium, Magnesium Hardness Ammonia Chloride Fluoride Sulfide 40 Please consider the environment before printing. 20

21 ph Measurement & Alkalinity Titration Requires electrode calibration Check slope, measure ph buffer Proper electrode storage ensures electrode responds quickly Fill port closed Electrode stored in storage solution not water, buffer solution or electrolyte! 41 ph Measurement & Alkalinity Titration If required to perform hydroxide, carbonate and bicarbonate alkalinity calculations automate as much as possible! Titration Result Hydroxide Alkalinity Carbonate Alkalinity Bicarbonate Alkalinity P = T P < 1/2T 0 2P T-2P P = 1/2T 0 2P 0 P > 1/2T 2P T 2(T - P) 0 P = T T 0 0 Can all be programmed into titration software 42 Please consider the environment before printing. 21

22 Hardness Titration Hardness Titration Applies to EPA and SM 2340C Complexometric titration using EDTA and color indicator Where s the endpoint? Challenges come with identifying the endpoint Color change is subjective Makes reproducibility difficult Colorblind? 43 Hardness Titration with the Optrode Using an optical sensor set to 610nm Typical titration curve below where endpoint is precisely identified Can automate titration, now! 44 Please consider the environment before printing. 22

23 Ammonia Using an Ion-Selective Electrode Measured potentiometrically using an ion-selective electrode EPA Combined electrode Measuring and reference electrode in one system Gas-permeable, hydrophobic membrane that separates the sample and the measuring electrolyte (<1% NH 4 Cl) 45 Review Ammonia Chemistry NH 3 + H 2 O NH 4 + OH - Excess strong base (NaOH) converts all NH 4 to NH 3 Dissolved NH 3 gas diffuses through membrane causing a mv change until partial pressure is identical Potential change is proportional to NH 3 in sample 46 Please consider the environment before printing. 23

24 Ion-Selective Electrode Care for Ammonia Rinse electrode after every measurement Condition in DI water for up to ~10 minutes between samples Low-level samples (<1 mg/l) may require up to 30 minutes Store properly For 1-5 days: Store electrode in 0.1M NH 4 Cl For >5 days: Store dry 47 Ion-Selective Electrode Care for Ammonia Before first measurement or after longer storage in dry state Soak inner glass electrode for 6-12 hours in ph 7 buffer After electrode has been fitted with new membrane Shake gently to remove any air bubbles from membrane Soak for 10 minutes in DI water 48 Please consider the environment before printing. 24

25 Tips for Better Ammonia Measurements Low-level samples will require more time to equilibrate High-level samples may require dilution because ammonia dissipates into the air Insert electrode into sample before adding hydroxide Drifting potential could mean: Membrane is damaged Wrong electrolyte Concentration >1 mol/l Temperature fluctuations 49 So Many Samples, So Little Time New Innovations in Sample Throughput 50 Please consider the environment before printing. 25

26 Challenges for High-Throughput Labs Short hold times Fast turnaround Emergency/priority samples Using an autotitrator can help but, what if you are already using one? Large batch sizes Multiple analysts required over multiple shifts 51 Solutions for Increasing Sample Throughput Dedicated Analyzer Routine analysis Automated QC Blanks, duplicates, spikes Standards Hands free, walk-away analysis Frees you up for other tasks! Ti-Touch Analyzer 52 Please consider the environment before printing. 26

27 Solutions for Increasing Sample Throughput Multi-Parameter Analyzer Combine several analytes into one system ph, Alkalinity, Conductivity, Hardness Ammonia, Fluoride Space saving Simplified data handling Environmental Analyzer 53 Solutions for Increasing Sample Throughput Expandable Analyzers Completely expandable and designed to grow with the needs of your laboratory From 18 to 175 samples Automate up to 4 analysis (different or same!) simultaneously OMNIS 54 Please consider the environment before printing. 27

28 Summary Titration can be improved by converting manual titrations to autotitrations Understanding how electrodes work improves troubleshooting practices Proper storage and calibration of electrodes is critical to ensuring accurate titration data Add a sample changer can improve repeatability, automate QC, reduce re-analysis and free up analysts to perform other tasks 55 Need Additional Information Communications@metrohmusa.com Web: Questions & Answer 56 Please consider the environment before printing. 28

29 Ask the Experts Jessica McVay Metrohm USA Lori Spafford Metrohm USA Enter your question into the question pane at the lower right hand side of the screen. Please include your name and specify to whom you are addressing the question. 57 Thank you for Joining this Webinar As part of your registration, you are entitled to an additional 30-day archive access of today s program. Don t forget to fill out the survey immediately following the webinar. 58 Please consider the environment before printing. 29

30 Presenter Biography Information Lori Spafford is the Product Manager for Titration for Metrohm USA. She has a Bachelor s Degree in Chemistry from St. Joseph s College in Indiana and over 10 years of experience in the chemical, food and beverage, and environmental industries. During her prior three years as an Applications Chemist at Metrohm USA, she has focused on the development of thermometric titration and has successfully brought innovative solutions to difficult applications in a variety of industries. Jessica graduated with a Bachelor of Science Degree in Forensic and Toxicological Chemistry from West Chester University of Pennsylvania. After graduating, her career started in the pharmaceutical industry as a QC chemist. She then moved to Florida to continue her career as an R&D chemist, developing new methods for generic drugs. At Metrohm USA, she is a technical support specialist. She uses her technical skills to help customers troubleshoot their instruments and/or software when they are in need of assistance. 59 CE Credits (CEUs) and Professional Development Hours (PDHs) AWWA awards webinar attendees CEUs. If you wish to take advantage of the opportunity to earn CEUs, visit Certificates will be available within 30 days of the webinar 60 Please consider the environment before printing. 30

31 How to Print Your Certificate of Completion Within 30 days of the webinar, login to or register on the website. If you are having problems, please Once logged in, go to: My Account My Transcript Information To print your official transcript, click Print list To print certificates, click Download certificate 61 Please consider the environment before printing. 31